【摘要】 研究了半掺杂相分离锰氧化物Eu0.5Sr0.5MnO3样品的结构和电磁输运特性.在半掺杂情况下,该样品呈O′型正交结构,表明样品存在典型的Jahn-Teller畸变;在75K附近样品的顺磁/反铁磁背景中开始出现铁磁相,在更低的温度42K,4000A/m磁场下M-T的场冷曲线和零场冷曲线出现明显分岔,样品的交流磁化率实部随温度的变化曲线中也在42K观察到尖峰的出现,表现出团簇玻璃行为.在无外加磁场下该样品在整个测量温区均呈现绝缘体型导电行为,而在外加磁场1.6×106A/m下出现磁场诱导的绝缘体—金属(I—M)转变,其电输运特性符合可变程跳跃模型;研究表明,半掺杂Eu0.5Sr0.5MnO3样品的基态存在多种复杂而丰富的磁相互作用之间的竞争机理,其研究将为强关联锰氧化物体系物理机理的理解提供丰富的实验资料.更多还原

【Abstract】 The structure,electrical and magnetic properties of the half doping phase separated Eu₀.5Sr₀.5MnO₃ manganite have been systematically studied.The results show that Eu₀.5Sr₀.5MnO₃ compound has the O’ orthorhombic structure and shows typical Jahn-Teller distortion.It is found that ferromagnetic phase turn up near 75 K and evident split of field cooling（FC）and zero field cooling（ZFC）under 4000 A/m is observed around 42 K.The ac susceptibility curve shows also a sharp peak around 42 K,indicating cluster-glass state rather than a spin glass state at 42 K.Meanwhile,throughout the measuring temperature range,the electric transport shows insulating behavior and there is no insulator-metal（I-M）transition.However,an applied magnetic field of 1.6×105 A/m can induce I-M transition.The conducting behavior of Eu₀.5Sr₀.5MnO₃ is well fitted by the Mott variable range hopping（VRH）model.All these phenomena indicate that for the ground state of Eu₀.5Sr₀.5MnO₃,there exists the competition mechanism of several complex magnetic interactions.The study provides abundant experimental information to underdtand the mechanism of the strongly electron correlated system.更多还原